Equalizing gauge wheel mechanisms for planters are well known. In such arrangements, a pair of ground-engaging gauge wheels are disposed on opposite, left and right sides of a furrow-forming opener, such as double-disc opener that uses a pair of downwardly and forwardly converging discs. The equalizing mechanism is such that when one of the gauge wheels encounters an obstruction causing the gauge wheel to rise, an equal and opposite reaction is created in the other gauge wheel, causing it to lower by the same amount. Therefore, the furrow opener and its supporting frame rise by only half the usual distance. Notwithstanding this equalizing action, the gauge wheels are height-adjusted by a common depth adjustment mechanism for setting the depth of ground penetration by the furrow opener. It is well known for such depth adjustment mechanisms to utilize a single swingable depth adjustment lever with a handle at its outer end which can be releasably latched in any selected one of a number of fore-and-aft positions corresponding to available depths.
However, with currently available furrow openers, it is possible that even though the depth adjustment levers of different row units on the machine may be set at the same indicated depth, manufacturing tolerances and unequal wear between the various row units may cause the furrow openers to actually operate at slightly different depths. Thus, even though the operator may believe that all seeds are being planted at the same, indicated depth on the multiple row units, in fact they may be planted at different depths, resulting in uneven emergence and other problems.
Accordingly, an important object of the present invention is to provide a way of calibrating a row unit having an equalizer mechanism associated with its gauge wheels so that the indicated running depth corresponds to the actual running depth. As a corollary to the foregoing, it is an important object to provide the user with a way of assuring that when multiple row units of the same machine are all set at a common indicated running depth, the actual running depth is in fact the same for all of the units across the machine.
Pursuant to these objectives, the equalizing gauge wheel mechanism of each row unit is connected to the depth adjustment lever of the unit by a special link that can be slightly adjustably lengthened or shortened as need be while the depth adjustment lever is set at a predetermined indicated depth. By appropriately adjusting the length of the link in this manner, the heights of the gauge wheels of all units relative to their furrow openers, and thus the depth of penetration of the furrow openers into the ground, can be brought into conformity with one another to assure that substantially the same actual depth of furrow opener penetration is achieved across all of the units for the same indicated depth at the depth adjustment levers.
In accordance with the present invention, a planter row unit comprises a frame; a furrow opener carried by the frame; a pair of wheel arms on opposite sides of said furrow opener, each of the wheel arms having an upper end, a lower end, and a pivotal attachment to the frame located intermediate the upper and lower ends for swinging movement about a generally horizontal, transverse axis; a ground-engaging gauge wheel rotatably attached to the lower end of each wheel arm respectively; a transverse equalizer bar interconnecting the upper ends of the wheel arms; a depth adjustment lever pivotally attached to the frame for swinging movement between any selected one of a plurality of predetermined, releasably latched positions; and a link interconnecting the depth adjustment lever and the equalizer bar for adjustably raising and lowering the gauge wheels relative to the furrow opener when the depth adjustment lever is released and shifted between the latched positions whereby to adjust the depth of said furrow opener, the link being selectively adjustable in length to permit depth calibration of the gauge wheels relative to the furrow opener when the depth adjustment lever is in a latched position.